A method for automatically relaying and distributing data to the whole network is, for example, a distribution method by flooding or a distribution method based on ad hoc routing.
Flooding is a method in which a communication node having received distribution data autonomously relays the distribution data one after another by using broadcast communication as in a bucket brigade. In distribution by flooding, there is no need to communicate data such as network control data for route construction other than data to actually distribute, and a bandwidth can be used only for distribution of the data to actually distribute. On the contrary, there is a problem that adding use of a bandwidth due to redundant relay of data between neighboring communication nodes easily occurs.
Further, flooding does not need a communication procedure relating to network control such as a communication procedure relating to route construction other than a procedure of transmission and reception of data to actually distribute, so that flooding is appropriate for communication between communication nodes including a high-speed mobile object. Although not only a simple flooding method but also a method for inhibiting adding use of a bandwidth is proposed herein, occurrence of excessive inhibition of data relay is anticipated even if which of the methods is used in a condition that the arrangement of communication nodes changes fast, for example, in a condition that a high-speed mobile object is included.
On the other hand, an ad hoc network is a wireless network which is temporarily formed by moving wireless communication devices and does not have a fixed infrastructure or a central management mechanism, and is also called Mobile Ad-hoc Network (referred to as MANET hereinafter). In ad hoc routing, a communication node autonomously relays distribution data on the basis of a route table generated by using a routing protocol for an ad hoc network.
A routing protocol is roughly divided into two types based on a timing to construct a route table. One of them is a proactive type that constructs a route by performing communication relating to network control for periodically causing a routing protocol to function independently of transmission and reception of data to actually distribute. The other is a reactive type that constructs a route by performing communication relating to network control for causing a routing protocol to function triggered by a request for transmission of data to actually distribute.
Such an ad hoc network is disclosed in Patent Document 1.    Patent Document 1: Japanese Unexamined Patent Application Publication No. JP-A 2006-500882
An ad hoc network requires a procedure of communication relating to network control for causing a routing protocol to function in addition to a procedure of transmission and reception of data to actually distribute as described above, and adding use of a bandwidth due to communication relating to network control occurs. Moreover, assuming communication between communication nodes including a high-speed mobile object, in a case where increase of the characteristic of following change of the arrangement of the nodes is intended, the proactive type requires a shorter interval to perform communication relating to network control, and the amount of adding use of a bandwidth due to communication relating to network control increases. On the other hand, the reactive type requires a procedure of communication relating to network control for route construction before transmission of data to actually distribute, and transmission of the data to actually distribute delays.
Thus, in constructing and maintaining an ad hoc wireless communication network which a plurality of wireless communication devices join, adding use of a bandwidth other than use of a bandwidth necessary for transmission and reception of data to actually distribute occurs. There is a problem that inhibiting such adding use of a bandwidth and increasing the characteristic of following a condition in which the arrangement of nodes largely changes, such as communication between communication nodes including a high-speed mobile object, are in a tradeoff relation and are hard to be compatible.